Malaria, also called maleita, palustre fever, impaludism, terçã fever or sezão, is a parasitic disease that, according to data from World Health Organization, affects about 300 million people in the world. It is considered to be, besides Aids, a world health problem. Malaria causes approximately 1 to 1.5 million deaths a year. It is one of the most important health problems nowadays, since its transmission occurs in almost 100 countries, in tropical and subtropical regions, inhabited by more than one third of the world population.
The distribution of the risk of malaria acquisition is not uniform within the same country and it is often unequal in areas situated in the same region, in addition, it is variable according to the seasons of the year and as time passes. In general, the risk is high in Africa (sub-Saharan area), South America (Amazon basin), Irian Jaia, Madagascar, Papua New Guinea, Southeast Asia and Vanuatu. It is sort of low in Afghanistan (East), Central America, South America (except in the Amazon basin), North America (rural areas of Mexico), China (north), Egypt, India, Indonesia, Iraq, Iran, Malaysia, Sri Lanka, South Iraq, Middle East, Pakistan and Arabian Peninsula (southeast). In Africa there are 90% of the cases of malaria, affecting, most of all, children under five years old, especially those who live in distant rural areas with little health assistance available. Malaria is endemic in Brazil where, annually, more than 400 thousand infected people are registered, the majority in the Amazon region.
Malaria is caused by a protozoan genus Plasmodium, which has about 100 species. Among these species only four of them affect humans, P. vivax, responsible for 80% of the current cases in Brazil, P. malariae which hardly ever occurs, P. falciparum responsible for a lethal and serious malaria if not rapidly and correctly treated, and P. ovale, not present in Brazil. Malaria is transmitted to mammals by insects: order Diptera, family Culicidae, and genus Anopheles. This genus comprehends about 400 species, but only a reduced number are important to the epidemiology of malaria in each region. In Brazil, five species are considered to be the main vectors: Anopheles darlingi, A. aquasalis, A. albitarsis, A. cruzi and A. bellator. 
The parasite is transmitted by the bite of the infected insect that inoculates the sporozoans, which get lodged in the hepatic tissue, when it comes to the human Plasmodium, they multiply intensively (a sporozoan generates from 10 thousand to 40 thousand schizonts within the hepatocyte). Released from the host cell, the parasites fall into the blood stream, invading and multiplying themselves in the red cells, provoking clinical manifestations of the disease, mainly intermittent fever, chronic headache, myalgia, anemia, breathing difficulties, convulsions and coma. In some regions of Africa a serious anemia is the common cause of infant mortality for some reason or another.
There are many classes of active antimalarial medicines against blood forms of the parasite. Among the more used antimalarials are: (a) the antifolates type I and II (e.g. pyrimethamine and sulfadoxine), which inhibit the parasite dihydrofolate reductase; (b) the aminoquinolines (e.g. chloroquine and amodiaquine); (c) the artemisinin derivatives (e.g. artesunate and arteeter) have as their most important site of action the digestive vacuole of the parasite. Primaquine acts against the hepatic forms of slow development common in P. vivax and responsible for relapses.
In the last decades the use of some blood schizonticides, in determined areas, became inefficient due to the emergence of resistance to them. Resistance to chloroquine, detected initially in the 1960's in Magdalena Valley, Colombia, and later in Vietnam and Brazil, is widely spread and will continue to appear in new areas, as it happened in Africa in the 1980's. As a solution to this problem, it was used again the quinine, a drug with high toxicity, and mefloquine, described by the American Armed Forces based on a selection of thousands of drugs derived from chloroquine. It was believed that mefloquine was a medicine 100% efficient against chloroquine-resistant parasites. However, P. falciparum developed resistance to mefloquine very fast, this fact was first observed in 1990, as well as other drugs commonly used. In the last 20 years, besides mefloquine, some drugs, such as halofantrine and artemisinin derivatives were developed to treat chloroquine-resistant P. falciparum. 
The combinations of drugs have been employed successfully in different classes of diseases, AIDS, cancer, and tuberculosis, for instance. This strategy of combination of drugs has also been employed with promising results against malaria. As an example, it can be cited the combination of artemisin derivatives with lumefantrine or doxycycline, as well as the combination of mefloquine with tetracycline or doxycycline (Wilairatana, P. et al. Archives of Medical Research, 2002, 33, 416). The combination of quinine and Fansidar (pyrimethamine and sulfadoxine) is employed to treat chloroquine-resistant P. falciparum. 
It is known that suppositories of artesunate provide fast response to fighting the parasite and fever in severe cases of P. Falciparum; however, the recrudescence rate is high. Mefloquine (1250 mg) is administered in order to prevent and reduce recrudescence [Looareeswan et al., Ann. Trop. Méd. Parasitol. 89, 1995, 469-475; Looareeswan et al., Jpn. J. Trop. Med. Hyg. 24 (Suppl. 1) 1996, 13-15].
However, as for the presence of multidrug-resistant P. Falciparum in many countries, the treatment of malaria with the drugs available nowadays is not always effective, the same happens to the chemoprophylaxis, not used in Brazil anymore.
It is noticed through patent documents WO9425436 and WO02083641, that research is being done in order to obtain amino derivatives. In the document WO02083641 these compounds may be combined with antimalarial compounds, such as quinolines (mefloquine) and antimalarial peroxides (artesunate).
This form of treatment, in which is used more than one medicine active in malaria treatment, even if one of them is new as previously reported, is susceptible of failure due to the resistance developed by the P. falciparum in relation to well-known drugs.
Hence, according to the increase in the resistance of this parasite, the research is absolutely necessary to develop new chemotherapeutic agents capable of fighting malaria effectively, which tends to aggravate with the planet global warmth and the deteriorating health system in many countries in tropic regions, where the disease is endemic.
The artesunate was developed in 1982 in China and the mefloquine in 1971, in the USA. According to what was previously presented, it is applied a combination of antimalarial drugs or polytherapy, e.g. the use of mefloquine and artesunate.
However, it has never been proposed to develop artesunate salts with quinolines, as it is described in the present invention, with antimalarial activity or against other diseases caused by other protozoans in order to overcome the difficulties pointed out. It is important to highlight that, since they are water soluble salts, the compounds of the invention allow a simplification in its formulation.